Which cellular structure is involved in the assembly of the spindle apparatus?

The centrosome is the primary cellular structure involved in the assembly of the spindle apparatus during cell division. It acts as a microtubule-organizing center, playing a crucial role in the formation of the mitotic spindle, which is essential for separating chromosomes and ensuring that each daughter cell receives an identical set of chromosomes.

During mitosis, the centrosome duplicates, and the two centrosomes move to opposite ends of the cell. They serve as anchors for the microtubules that extend toward the chromosomes, facilitating their alignment and eventual separation. The organized structure of the spindle apparatus is critical for proper chromosome distribution, and defects in this process can lead to uneven chromosome segregation.

In contrast, the nucleus primarily contains the cell's genetic material and is involved in processes like transcription and replication but does not play a direct role in spindle assembly. Ribosomes are the sites of protein synthesis and are not involved in any aspect of cell division. The Golgi apparatus is involved in modifying, sorting, and packaging proteins and lipids for secretion or use within the cell, but it does not participate in spindle assembly.